#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>

int main()
{
	int a[100], n, low, high, target, mid, idex = -1;
	scanf("%d", &n);
	low = 0;
	high = n - 1;
	target = 0;
	mid = (low + high) / 2;
    for (int i = 0; i < n; i++) {
			scanf("%d", &a[i]);
	}
	scanf("%d", &target);
	while (low <= high) {
		if (target == a[mid]) {
			idex = mid;
			break;
		}
		else if (target < a[mid]) {
			high = mid - 1;
			mid = (low + high) / 2;
		}
		else if (target > a[mid]) {
			low = mid + 1;
			mid = (low + high) / 2;
		}
	}
	if (low > high) {
		printf("None");
	}
	else printf("%d", idex + 1);
	return 0;
}